N: 40 S: -40 E: 180 W: -180
Description
This Level 1 (L1) dataset contains the Version 2.0 geo-located Delay Doppler Maps (DDMs) calibrated into Power Received (Watts) and Bistatic Radar Cross Section (BRCS) expressed in units of m^2 from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. This version supersedes Version 1.1. The L1 dataset contains a number of other engineering and science measurement parameters, including sets of quality flags/indicators, error estimates, and bias estimates as well as a variety of orbital, spacecraft/sensor health, timekeeping, and geolocation parameters. At most, 8 netCDF data files (each file corresponding to a unique spacecraft in the CYGNSS constellation) are provided each day; under nominal conditions, there are typically 6-8 spacecraft retrieving data each day, but this can be maximized to 8 spacecraft under special circumstances in which higher than normal retrieval frequency is needed (i.e., during tropical storms and or hurricanes). Latency is approximately 6 days (or better) from the last recorded measurement time. The Version 2.0 release represents the first science-quality release that has moved beyond the previous "Provisional" releases (i.e., Version 1.0 and 1.1). Here is a summary of improvements that reflect the quality of the Version 2.0 data release: 1) more accurate estimates of the transmitter power of each GPS satellite; 2) more accurate estimates of the transmitter antenna radiation patterns of each GPS satellite; 3) more accurate determination of the delay and Doppler coordinates of the specular point in each DDM; 4) Correction for variations in the GPS antenna gain pattern across the DDM (v1.1 assumed the gain at the specular point for all parts of the DDM); 5) Correction for variations in the GPS signal propagation range with altitude of the CYGNSS satellites (v1.1 assumed a constant range consistent with the average orbit altitude); 6) more accurate determination of the receiver antenna radiation patterns on the port and starboard side of each CYGNSS satellite; 7) better quality control flagging for increased uncertainty in CYGNSS satellite attitude knowledge during start tracker sun outages.
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